Category Archive: Uncategorized

Upgrades and Denitrification System Installed at Doswell Treatment Plant

The Doswell Virginia Wastewater Treatment Plant was built to handle water treatment for the Bear Island Paper Mill that began operations in 1979, and the increasing demands from the Paramount Theme Park (formerly King’s Dominion). The demands at this facility have continued to increase as more residents moved into the area. A Natural Gas Power Plant built in 1991 also significantly increased demand. The current wastewater treatment capacity of this facility is 1MGD (one million gallons per day). Waco successfully completed two projects here, greatly improving existing plant operations while providing for future expansion.

WIP III Upgrades for the Doswell Wastewater Treatment Plant

In 2023, Waco began the WIP III Upgrades project, which included the construction of a denitrification process to meet new ENR (Enhanced Nutrient Removal) regulations. These regulations were implemented by Virginia’s DEQ to further remove nitrate-nitrogen from water discharged into the North Anna River, within the Chesapeake Bay watershed. Because this was an existing operating facility, all work was performed while maintaining flow through the plant. Power and existing communications systems (SCADA) had to be kept active throughout the course of the project until the new systems were brought online.

To accomplish these new requirements at Doswell, Waco renovated the existing aeration basins by installing a new aeration system, complete with blowers, piping, diffuser grids and intermediate baffle walls. The existing blower building adjacent to the basins was converted into an electrical room that housed control panels, VFDs and electrical gear for the new equipment. Repairs were also made to the existing primary clarifiers by converting them into pre-anoxic tanks with separate bubbler systems. A new cast-in-place splitter box was installed upstream, with slide gates that direct the flow to each basin. Waco self-performed all concrete work, above ground mechanical piping and equipment installation, and managed the underground piping, electrical, HVAC, and SCADA upgrades.

Downstream of the aeration basins, existing underground piping was modified to add an intermediate pump station (including two pre-cast wet wells and valve vaults) that would pump flow into the new Denitrification facility. A pre-cast overflow vault was also added to the main line so the plant could bypass the pump station and denitrification facility during peak flow periods to prevent the facility from flooding. Waco installed a new concrete pad for access to the wet wells and valves vaults, along with the wet well pumps, piping and valves.

A 4,500 SF pre-engineered metal building was erected to house the denitrification equipment, consisting of sixteen skid mounted tanks (4 tanks/ skid), a 4,000-gallon polyethylene clear well, blowers, pumps, and interconnecting piping. A new electrical room supported the new system and related components. Waco installed the foundation pad for this facility and managed the installation of the building, plumbing, electrical, structural platforms, HVAC and controls. Once the structure was erected and dried in, Waco installed the skid mounted tanks, clear well and interconnecting piping and successfully coordinated with all parties to bring the new system online.

To support the new Denitrification process, separate buildings were constructed on site for methanol and aluminum chemical feed. The methanol facility consisted of a pre-engineered metal building to house the transfer and chemical pumps, with an electrical room and a fire suppression system – all of which were connected to two stainless steel methanol tanks in a containment basin adjacent to the building. The aluminum facility consisted of a separate pre-engineered metal building that housed chemical pumps, electrical gear and controls – all connected to a fiberglass storage tank in another containment basin adjacent to that building. Waco self-performed all concrete work including the building foundations and containment basins for the storage tanks, and installed the tanks, piping and equipment.

Downstream of the denitrification facility, a post-aeration structure was added to the existing effluent line. This consisted of a 20-foot deep cast-in-place structure with slide gates, blowers and aeration diffusers. Waco installed a temporary bypass system to maintain the flow during the construction. Waco self-performed the concrete work and installed the blowers, diffuser piping and slide gates.

The project also included upgrades to the existing control building with a new motor control center and associated panels, and a new backup power generator. In addition, the entire SCADA system was upgraded with a new communication loop throughout the entire site. As each new system was brought online, Waco oversaw the coordination to ensure a successful operation.

While on site, Waco was also requested to rehabilitate an existing secondary clarifier that had been out of service for years. This work involved demolishing the existing center column, arms and bridge and replacing it with new components.

Structures and Equipment installed:

• Splitter Box – (1) new Splitter box structure with (2) slide gates and associated piping and valves
• Aeration Basins- (2) 30 HP blowers, (2) 20 HP blowers, (2) 25 HP rotary lobe pumps, all new aeration headers and piping, new instrumentation also converted old blower building to an electrical room with new VFDs and controls.
• Intermediate Pump Station- (2) precast wet wells, (2) precast valve vaults and (4) 8.5 HP submersible pumps with associated piping, valves and controls
• Denitrification- (1) 4,500 SF pre-engineered metal building, (4) pre-fabricated filter skids, (1) backwash pump and blower skid, (1) 4,000 gal. clear well, with associated piping, valves and instrumentation. New steel platform around filter skids, HVAC in building and attached electrical room with VFDs, power panels and controls.
• Post Aeration- (1) new post-aeration structure w/ (2) 3HP blowers, associated air piping and valves and (6) slide gates
• Methanol- (1) 550 SF pre-engineered metal building with (2) 5,500-gallon stainless steel storage tanks, (4) ½ HP diaphragm chemical metering pumps, (2) 2-HP transfer pumps, (1) chemical sump pump, with associated piping, valves and instrumentation, new HVAC, fire suppression system, and electrical room with VFDs, power panels and controls
• Aluminum Sulfate- (1) 250 SF pre-engineered metal building with (1) 6,000 gal. FRP storage tank, (4) peristaltic tube metering pumps, (1) chemical sump pump, new HVAC, power panels and controls
• Existing Control Room – renovated existing control room with new MCC, new entry doors and replaced existing generator with new 600kW generator.
• Significant site work, all new underground piping between buildings and about 2,000 LF of new underground duct banks
• Insulation system for methanol tanks and piping.

Project Manager: Dan Coon
Superintendent: Rich Foster
Project Engineer: Will Wake
Project Value: $18.3 MM

Doswell WWTP Belt Press Replacement

Waco was also awarded the Doswell WWTP Belt Press Replacement contract, which was completed during the construction of the WIP III Upgrades project. This project included the installation of a new belt filter press, polymer system, and sludge cake pump in the existing Belt Press building. These upgrades helped improve the dewatering process and reduce the sludge volume produced at the plant, ultimately reducing costs of storage and transportation of sludge. Coordination between projects was required as the existing sludge pumps feeding the Belt Press received new VFDs as part of the WIP III Upgrades project. Waco successfully coordinated all parties involved to install the new equipment, controls and communications, to improve the efficiency of the system.

Project Manager: Matt Moore
Superintendent: Rich Foster
Project Engineer: Will Wake
Project Value: $417,000

Lead Removal – Firing Ranges

Firing ranges have been growing in popularity as more people want to better understand how to properly and safely utilize their firearms. Also, in order for police forces, security guards and the military to continually improve performance, they need better access and training.

Virginia offers several types of firing ranges:

• open to the general public
• enhanced training facilities built for police, military and security operations.
• private gun clubs.

When in operation, all of these facilities will generate some amount of lead contamination.

In outdoor ranges the embankment or structure behind the targets can accumulate fired lead bullets. It is best to have a periodic maintenance schedule to prevent any leaching of the lead from these structures into the surrounding soils. Remediation on typically earthen embankments involves digging into or removal of portions of the soil and sifting out the lead bullets.

Indoor firing ranges will require a more extensive cleaning. The horizontal and vertical surfaces around the shooting area will accumulate lead dust discharged from the rounds being fired. Most modern ranges have an advanced air filtering duct system which will require removing the filters contaminated with lead, cleaning the surrounding surfaces and replacing with new air filters. The filter replacement can be just the pre-filters and secondary filters during a regular scheduled clean-up to a full scale replacement of the HEPA filters during an annual or semi-annual cleaning. Typically, a lead remediation company will develop a process to sift thru the different products or medias that these ranges have behind the targets. The collected lead from the fired bullets will be safely disposed of in a proper landfill.

Many new firing ranges have made significant improvements to both the lead bullet retrieval system and the control of lead dust in the air of these facilities. The new technology of so called “Bullet Banks” capture the spent bullets in tanks or containers. They also incorporate a direct link to the ventilation and exhaust system, so that clean air can be provided back into the shooting area.

All lead should be removed using specifications determined by the state or county for safe remediation and disposal. OSHA provides a specific standard (29-CFR 1910.1925) for determining airborne exposure to lead.

Waco has many years of experience cleaning and maintaining lead in firing ranges, both private and public. We ensure that all members of our teams have the proper annual Lead certifications that are required. We have dedicated HEPA vacuums for lead and utilize all the best practices for safe removal and disposal of lead.

Waco currently maintains schedules for the quarterly, annual or semi -annual cleaning of the following facilities:

VCU Police Security Center – Richmond, Virginia
Richmond Police Training Academy – Richmond, Virginia
Albemarle County Firearms Training Center – Charlottesville, Virginia

Contact Waco today, for safe, cost-effective maintenance of lead in your firing range facilities.

OSHA Lead Standards For Indoor Firing Ranges

Process Piping Systems

Specialized equipment installed in manufacturing facilities will require mechanical piping systems that are engineered to handle the rigorous conditions of their processes. Some of these conditions are:

• Temperatures: (Cryogenic -267F to Saturated Steam 2000F plus)
• Pressures: (Vacuum to HP steam at 2,000 psig )
• Fluid types: Acids, caustics, corrosive and flammable chemicals, at various viscosities

Controlling these conditions are critical and can involve a multitude of different types of steel piping, gaskets, valves, flanges and fittings.

Most of the design requirements for Process Piping Systems are covered under ASME B31.3 codes.
This code will provide the roadmap for piping design in chemical, petrochemical, pharmaceutical, paper mills, mining, semiconductor and food & beverage manufacturing facilities.
Similarly, ASME B31.1 codes provide a complete design guide for Power Piping Systems, which include most power generating facilities and industrial plants utilizing high pressure steam.

The specifications for what type of piping metallurgy to be used is dictated by these ASME codes. The various types of metallurgy are:

• Stainless Steel: grades 304, 316, P11, P22, P-91, Chrome -Moly, Inconel, Hastelloy and Monel
• Carbon Steel: Schedule 5 thru 160. Seamless or welded. The higher the number; the greater the pressure resistance and the thicker the pipe wall dimension.

B36.10 is the specification for carbon steel pipe dimensions
B36.19 is the specification for stainless steel pipe dimensions
ASTM A270 is the material specification for hygienic sanitary stainless steel pipe and tubing

The contractor may determine what type of connection system will be utilized depending on the application. If the process requires welding the piping, then the most common welding methods are:

Gas Metal Arc- GMAW / MIG Gas Tungsten Arc – GTAW/ TIG
Shielded Metal Arc – SMAW / Stick
Flux Core Arc – FCAW

Most process piping systems incorporate both fitted pipe connections and welded pipe connections. The welded pipe connections are usually butt weld or socket weld. These welds typically connect the piping to flanges, valves or tee’s and fittings.

The testing of these pipe systems is usually one of the following:
Non-Destructive – Liquid Dye Penetrant, Ultrasonic or Radiography
Hydrostatic – which is a pressure test using water.

The true formula for ensuring the success and longevity of a process piping system requires strict adherence to the ASME codes listed under B31.1 and B31.3 and documentation of the process (which should involve an approved Quality Assurance and Quality Control Manual.) This will demonstrate the experience and skill of the welders, certify the origin of purchased materials including traceability and the inspection and testing of the entire piping system.

Waco has built our reputation on providing these components in every application, whether large or small, and we will continue these efforts on all future projects.

Contact us today to discuss how we can be of service to you on your next process piping application.

Freeze Protection of Piping

Freeze protection of water piping located outside or exposed to cold temperatures requires planning and adherence to proper specifications. Thermal insulation alone, even when applied correctly and in the proper thickness, does not necessarily prevent freezing. All electrical heat tracing manufacturers provide a specific heat loss calculation chart for selecting the proper heat trace wattage, based on the pipe diameter and insulation thickness. It is important to use the correct wattage rating from these charts.

The most common wattages used for freeze protection of water piping are 3, 5, and 8 watts per foot. In some instances, 10 and 15 watts per foot may be required. Small-diameter piping (3 inches or less), hung horizontally, is more susceptible to freezing than vertical piping of the same diameter, however, both should be treated equally for the protection of the entire system. Flanges, valves, and instrumentation all must have the electric tracing looped or installed properly to eliminate cold spots or gaps in the system. Environmental factors such as wind speed, minimum ambient temperature, and the location of the piping can require a different level of protection (e.g. piping located on a roof vs. buried in the ground).

Fortunately, many regions of the Mid-Atlantic where Waco operates, do not experience long extended periods of below-freezing temperatures. However, a polar vortex situation like the one that occurred around Christmas in 2022 did not take long to cause serious problems for many businesses and factories.

What are the piping systems that are most susceptible to freezing?

• Hydronic water piping on HVAC units and cooling towers
• Makeup water piping and exposed plumbing
• Wastewater piping at Water Treatment Plants
• Water piping at Pump Stations or Industrial facilities

The main type of electric tracing for freeze protection is called self-regulating (SR) and is designed to operate with demand, fluctuating or increasing the wattage as the temperature drops. Another type of electric tracing is Constant Wattage (CW), which is commonly used to maintain a constant specified temperature in water or liquids of a process system. Heat tracing can be powered by any of the voltages commonly found in commercial or industrial facilities (120, 208, 240, and 277) but must be ordered for the specific voltage available.

Insulation contractors like Waco, Inc. are very capable of effectively installing SR electric heat tracing and providing the proper insulation and weather barrier jacketing systems. It is a complete package that clients find more cost-effective than getting separate bids for heat tracing and insulation from different contractors. A qualified electrician is required to make the final connection to the power source on any system involved. Waco works with several electrical contractors to ensure that the tracing is properly installed and that junction boxes and thermostats are located in such a way to reduce the lengths of conduit needed to power them. Sometimes heat tracing may need to be located in a hazardous environment, which would require Class 1, 2, or 3 explosion-proof electrical enclosures. Waco can provide systems with additional ground fault protection, in addition to heat trace cable manufactured with corrosion-resistant material or non-sparking, non-metallic design.

Any thermal insulation system must be properly installed so that the heat tracing can perform as designed. Adequate protection from the weather is critical. Waco has decades of experience with heat-trace systems, and we continually train our workforce on proper installation techniques. You can be assured that we will provide a complete system that performs and protects, reducing your worries during the winter months and throughout the year. Don’t wait until cold weather arrives. Contact Waco for your next heat tracing project.

Sanitary Stainless Steel Piping Systems

Due to its highly corrosion-resistant nature, the requirement to provide a hygienic environment for both liquids and air service to a process will often involve sanitary stainless steel. The industries that demand a sterile microbiological-free system can be found in Aerospace, Semi-Conductor, Food & Beverage, Pharmaceutical and Personal Care. Some facilities, such as Nuclear and other power generating plants may not have the same need for a biological free environment but require the other benefits found in a sanitary stainless-steel system, such as the durability of the steel.

Sanitary Stainless steel piping systems typically have welded joints with elongated bends and are so designed so that there is a smooth transition from section to section and, therefore, contaminants cannot accumulate. The welds need to be smooth and have full penetration inside and precautions must be made to prevent oxidation during welding. Most Sanitary Stainless-Steel systems use a grade of steel that is either 304 or 316. This type of steel contains Chromium Oxide which protects the sheets or piping components from corrosion or contamination. Welding processes that keep a consistent temperature and exhibit a lower heat input will help maintain the proper amount of Chromium in the steel. Inert gases such as Argon or Helium are commonly used to create this type of welding condition. Orbital welding systems are very precise and reliable due to their speed, consistency and ability to perform most welding in a sterile environment with limited human involvement.

Borescope testing (fiber optics) is frequently required on sanitary stainless steel piping to insure that the interior welds on the piping can be visually seen and confirm that there is a smooth surface with no pits, cracks or areas where contaminants could accumulate. Passivation or pickling can additionally be performed if further hygienic cleaning of the pipe is required.

Discoloration around the welds is often a good indicator of potential corrosion hazards in a sanitary stainless-steel system and should be kept to a minimum or eliminated.

The fabrication and installation of sanitary stainless-steel piping, fittings, valves and equipment requires a contractor’s commitment to extreme quality assurance, proper documentation, verifiable traceability of materials and the ability to provide assistance to the facility during commissioning and start up. Waco has trained welders who are practiced at sanitary stainless steel welding processes. We have a trained QA/ QC staff that keeps updated on current requirements and certifications. We have a quality system in place that streamlines the entire process from design to product delivery.

Water & Wastewater System Processes

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Water Treatment and Wastewater Treatment processes are significantly different from each other.  This article will explain both and demonstrate some of the differences.

Water Treatment systems are typically designed to take fresh water from a body of water, well or aquifer to a storage tank.  Filters systems in combination with flocculant clarifiers and/or coagulants are used to remove sedimentation. Biocides and chlorine treatment may be added to control bacteria and biological microbes.  Additional chemicals may be added to balance PH levels.

Wastewater processes, on the other hand, require extensive additional treatment, which involves screening, filtration, aeration and chemical additive equipment.  There has been significant new technology involving optimization of the treatment process for both of the solid and liquid components in Wastewater systems.

Waco has been on the forefront of correctly implementing these new engineered designs.  The combination of advanced technology and Waco’s construction expertise has provided vitally important environmental improvements to both Water and Wastewater treatment systems.  These are the challenges facing today’s growing municipalities, counties and industrial manufacturers charged with Water and Wastewater facility management.  We will explain what systems Waco currently constructs and how this is benefiting our communities, parks, waterways and wildlife management areas.

Water Treatment:

Fresh Water – Pump Stations:    These facilities are typically installed to increase the amount of water required for a certain municipality or county’s system.  Most require a large holding tank of fresh water, large pumps and a piping system.  Typically, Pump Stations receive water that has previously been treated. In some cases, chlorine might be added or additional chemical treatment for ph control may be required.  The main function of a Pump Station is to maintain water pressure and water capacity.

Waco has installed many of these Pump Stations throughout Virginia and has a solid reputation for competitively bidding and completing this work ahead of schedule.  We have a dedicated team that works exclusively on these types of projects.  We understand the means and methods used to install the equipment and ensure the proper scheduling of the work.  We understand the construction process, how to properly install the equipment and schedule the work.  We can foresee potential problems and bring them to the attention of the owner before they delay the project or incur additional expense.  We have warehouse facilities capable of storing long lead time parts and equipment, further maintaining our ability to keep the project on schedule.

Waste Water Treatment

Types of Water & Wastewater Treatment Facilities being constructed

• Odor Control Stations
• Municipal Wastewater Treatment Plants
• Industrial Onsite Wastewater Treatment Facilities

Odor Control Stations:

Sewage treatment facilities can be located in densely populated areas.  It is critical that the facility operates with the least amount of released odors as possible.  Odor control is performed with many methods, but the most commonly used is a Bio-Scrubber system.  This system gathers vapors from the wet well using industrial fans, and adds chemicals and water to the vapors which are then sent through a bio filter system. These tanks and filters collect enough of the hydrogen sulfide gas so that any discharge out the stack has a minimal amount of odor.
Recent projects;

Municipal Wastewater Treatment Facility

Main processes for cleaning Wastewater

Physical – This involves large screens, centrifuges, clarifiers, aeration or blower air, Nano membranes or filter media types and reverse osmosis.

Chemical – This involves treating the water with chemicals such as lime, bleach/chlorine, hypochlorite, ozone or several other types of disinfectant.

Biological – naturally occurring microbes or organic matter that breaks down the pathogens or wastes into components that can be further treated with less chemicals required. Anaerobic Digestion process.

Newer Technologies – UV Light

Goal:  To separate the solids from the liquids

Liquids typically go through a multi stage filtering and aeration process. Chemicals are added along the way until the wastewater is considered fresh potable water and suitable for discharge back into the environment.

Solids will go through a more involved filter pressing and heating process to drive more liquid out of the solid and make it into what is commonly called a “cake”. Once it gets to this stage it is a biosolid or sewage sludge.   An anaerobic digestion process uses naturally occurring bacteria to convert organic matter (sewage sludge) into methane and carbon dioxide. These components methane and CO2 are often referred to as Biogas.  The methane can be burned off using a thermal oxidizer, or it can be used in a combustion process to convert to a useful energy source for operating segments of the Wastewater Treatment facility.

The biosolids are further chemically treated until the level of pathogens has been reduced to an allowable limit set by EPA and other agencies.  This final product (ammonia/nitrogen rich solids) can then either be used on soils for agricultural purposes or for reclamation sites or landfill cover.  The current breakdown of biosolids application in the US is – Agricultural – 42%, Landfill or reclamation soil – 43%, and Incineration – 15%

Industrial Onsite Wastewater Treatment Facilities

Many industrial manufacturers are required to pre-treat their chemical discharge before sending it to a municipal or county wastewater treatment plant.  Waco’s long history of experience working in industrial plants and our combined wastewater capabilities allow us to provide a combined approach that many other contractors cannot offer.

Experience

Waco has the ability to perform major upgrades to existing operational wastewater treatment facilities.  We have an extensive completed project list and over 40 years of experience in this segment of the construction business. Our jobs range from minor equipment change outs of $50,000 to large $10 million to $18 million projects involving installation of entire new buildings with filtering and chemical processing equipment.  We specialize in increasing the capacity of a wastewater treatment facility, or constructing components to bring an existing facility into compliance with new water regulation codes, or for reissuance of permits, such as the Virginia Pollution Discharge Elimination System (VPDES).
All this work can be done while the facility is operating. Coordinating with plant operators and engineers is critical, especially when the final connections between the older system components are made with newly installed systems.  Other factors such as stormwater control measures and modifications to roadways are elements that must be considered before implementation of any construction process.

Conclusion

Water and Wastewater treatment facilities will continue to see increasing demands.  Waco incorporates these new technologies into the project, and has the ability to implement those requirements in a coordinated construction process.  We work with the top Water and Wastewater treatment engineering firms, and invite you to review our past projects or contact a reference from our extensive list of clients.

Recent projects:

Huguenot Road Pump Station
Ridge Road Pump Station
Town of Crew 
Vent station overhaul at Creighton Road
Incinerator Upgrades for Wastewater Treatment Facility
Maintenance Cost and Odor Reduction at Waste Treatment Facility

Click here for more information about Waco’s Water and Wastewater Treatment capabilities.

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